4
Some Pushes and Pops
l
Initially S =
L
l
Push( d, S)
l
Push( b, S)
l
Push( c, S)
l
Pop(result, S)
l
Push( a, S)
l
Length_of(S)
l
L
l
D
l
bd
l
cbd
l
bd
l
abd
l
3